This invention relates to a vibration absorbing structure for an outboard motor and more particularly to an improved damping arrangement for damping certain types of vibrations in marine outboard drives.
In conventional marine outboard drives such as outboard motors, the drive shaft housing is resiliently connected to a steering shaft by means of annular elastic bushings that have their axes disposed parallel to the propeller shaft axis. These elastic bushings are very effective in dampening the driving thrust transmitted from the outboard drive to the hull of the associated watercraft. However, there are other types of vibrational forces that are not effectively dampened by these members. For example, torsional vibrations can cause rotational couples about the drive shaft axis and irregular combustion can give rise to couples in the same general direction. If the elastic bushings that connect the drive shaft housing to the steering shaft are made resilient enough to dampen these forces, then there is too much elasticity in the system. This will result in such undesirable effects as unstable straight running, low steering response and propulsion unit oscillations.
It is, therefore, a principal object of this invention to provide an improved vibration damping arrangement for a marine outboard drive.
It is a further object of this invention to provide a damping arrangement for a marine outboard drive which permits not only the damping of propulsion unit thrust, but also couples which may be exerted on the outboard drive without adding excessive elasticity into the system.